Could you consider adding a "hook" which calls an optional user-supplied PHP functionwhich would allow a re-write of the URL string, and use the resulting string as the outputinto the sitemap?

I would like my sitemaps to contain SE "friendlier" forms, instead of the parameter-fulforms found my traversing the site. A display-form post-processing function would allow that, as in the way a ".htaccess" rewrite might do.

I would not recommend to rewrite URLs in this way. As long as Sitemap generator script is able to find your "unrewritten" links, the search engine bots will find them too, despite the fact that sitemap includes "se freindly" links.

I intend to use .htaccess to re-write the SE friendly URLs into the internal arg-laden form for site visitors.

Your generator does exceptionally well at traversing the internal forms, and external botswill too, but I would like to have the ability to have the output files contain the SE friendly formof each URL by calling an optional last-moment-final-display-filter hook. This yields a much-more appealing set of URLs for the sitemap.html file for example.